3P-Weibull Rank Regression
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This example validates the calculations for 3-parameter Weibull with rank regression in Weibull++ standard folios.
Reference Case
Table 6.3 on page 292 in the book Reliability Engineering Handbook Vol 1 by Dr. Kececioglu, Prentice-Hall, 1991.
Data
| Num. in State | State F or S | Time to Failure |
|---|---|---|
| 1 | F | 46 |
| 1 | F | 64 |
| 1 | F | 83 |
| 1 | F | 105 |
| 1 | F | 123 |
| 1 | F | 150 |
| 4 | S | 200 |
Result
In the book, the results are obtained by visually fitting a straight line to the median rank at each failure point. The reliability function for a 3P-Weibull distribution is:
The results are 
= 1.2,
= 144 and
= 30
Results in Weibull++
